Halosilicate phosphor and white light emitting device including the same

ABSTRACT

A halosilicate phosphor represented by Formula 1 
       p(Ca 1-x M 1   x )O.qM 2 O 2 .rM 3 A 2 :sM 4            wherein M 1  includes at least one selected from a group consisting of Sr 2+  and Ba 2+ ; M 2  includes at least one selected from a group consisting of Si 4+  and Ge 4+ ; M 3  includes at least one selected from a group consisting of Ca 2+ , Sr 2+  and Ba 2+ ; M 4  includes at least one selected from a group consisting of Eu 2+ , Mn 2+ , Sb 2+ , Ce 3+ , Pr 3+ , Nd 3+ , Sm 3+ , Tb 3+ , Dy 3+ , Ho 3+ , Er 3+ , Yb 3+  and Bi 3+ ; A includes at least on selected from a group consisting of F − , Cl − , Br −  and I − ; and wherein 0≦x&lt;1, 1.8≦p≦2.2, 0.8≦q≦1.2, 1&lt;r/q&lt;3 and 0&lt;s&lt;0.5.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No.10-2008-0129410, filed on Dec. 18, 2008 and all the benefits accruingtherefrom under 35 U.S.C. §119, the content of which in its entirety isherein incorporated by reference.

BACKGROUND

1. Field

The following disclosure relates to a halosilicate phosphor and a whitelight emitting device including the halosilicate phosphor. Moreparticularly, one or more exemplary embodiments relate to a halosilicatephosphor having a large full width at half maximum (“FWHM”) and a whitelight emitting device including the halosilicate phosphor.

2. Description of the Related Art

A conventional optical system may include fluorescent lamps orincandescent lamps. Fluorescent lamps, however, cause environmentalproblems due to high levels of mercury (Hg) included therein. Also,conventional optical systems have very short lifetimes and/or lowefficiencies and thus are unsuitable for use energy saving applications.Therefore, research is being performed to develop white light emittingdevices having high efficiencies and extended lifetimes.

White light emitting devices are able to produce white light using threemethods as follows. In one method, red, green and blue phosphors may beexcited by an ultraviolet light emitting diode (“UV LED”) acting as alight source to produce the white light. In another method, red andgreen phosphors may be excited by a blue light emitting diode (“LED”)acting as a light source to produce the white light. In the last method,a yellow phosphor may be excited by a blue LED acting as a light sourceto produce the white light.

According to the method for producing white light by exciting a yellowphosphor using a blue LED as a light source, the white light isgenerally produced by combining the blue LED with Y₃Al₅O₁₂:Ce³⁺,Tb₃Al₅O₁₂:Ce³⁺, (Sr,Ba)₂SiO₄:Eu²⁺, or the like as the yellow phosphor.In particular, Y₃Al₅O₁₂:Ce³⁺ is known as a phosphor suitable for use ina white light emitting device due to its excellent efficiency and wideemitting bands. However, the color rendering properties of theY₃Al₅O₁₂:Ce³⁺ phosphor are generally insufficient, and thus only coldwhite light may be generated using this method due to an insufficientred light emission.

To address the above deficiencies, a silicate-based phosphor has beendeveloped to be used as an orange-yellow phosphor. A white lightemitting device generating white light by exciting the silicate-basedphosphor using a blue LED light source is known.

SUMMARY

One or more exemplary embodiments include a halosilicate phosphor havinga large full width at half maximum (“FWHM”).

One or more exemplary embodiments include a method of preparing thehalosilicate phosphor.

One or more exemplary embodiments include a white light emitting devicethat includes the halosilicate phosphor and thus has excellent colorrendering properties.

Additional aspects, advantages and features will be set forth in part inthe description which follows and, in part, will be apparent from thedescription, or may be learned by practice of the invention.

To achieve the above and/or other aspects, one or more embodiments mayinclude a halosilicate phosphor represented by Formula 1.

p(Ca_(1-x)M¹ _(x))O.qM²O₂.rM³A₂:sM⁴

wherein M¹ comprises at least one selected from a group consisting ofSr²⁺ and Ba²⁺, M² comprises at least one selected from a groupconsisting of Si⁴⁺ and Ge⁴⁺, M³ comprises at least one selected from agroup consisting of Ca²⁺, Sr²⁺ and Ba²⁺, M⁴ comprises at least oneselected from a group consisting of Eu²⁺, Mn²⁺, Sb²⁺, Ce³⁺, Pr³⁺, Nd³⁺,Sm³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Er³⁺, Yb³⁺ and Bi³⁺, A comprises at least oneselected from a group consisting of F⁻, Cl⁻, Br⁻ and I⁻, 0≦x<1,1.8≦p≦2.2, 0.8≦q≦1.2, 1<r/q<3 and 0<s<0.5.

In one exemplary embodiment the halosilicate phosphor may have a FWHM ofabout 125 nm to about 220 nm in emission spectra.

To achieve the above and/or other aspects, one or more exemplaryembodiments include a white light emitting device including a lightemitting diode (“LED”) and the halosilicate phosphor.

In one exemplary embodiment the LED may be either a blue LED or anultraviolet light emitting diode (“UV LED”).

In one exemplary embodiment the white light emitting device may furtherinclude at least one selected from a group consisting of a bluephosphor, a green phosphor and a red phosphor.

The blue phosphor may include at least one selected from a groupconsisting of (Sr,Ba,Ca)₅(PO₄)₃Cl:Eu²⁺; BaMg₂Al₁₆O₂₇:Eu²⁺;Sr₄Al₁₄O₂₅:Eu²⁺; BaAl₈O₁₃:Eu²⁺; BaMgAl₁₀O₁₇:Eu²⁺ andSr₂Si₃O₈.2SrCl₂:Eu²⁺; and Ba₃MgSi₂O₈:Eu²⁺ and(Sr,Ca)₁₀(PO₄)₆.nB₂O₃:Eu²⁺.

The green phosphor may include at least one selected from a groupconsisting of (Ba,Sr,Ca)₂SiO₄:Eu²⁺; Ba₂MgSi₂O₇:Eu²⁺; Ba₂ZnSi₂O₇:Eu²⁺;BaAl₂O₄:Eu²⁺; SrAl₂O₄:Eu²⁺; BaMgAl₁₀O₁₇:Eu²⁺, Mn²⁺; andBaMg₂Al₁₆O₂₇:Eu²⁺, Mn²⁺.

The red phosphor may include at least one selected from a groupconsisting of (Ba,Sr,Ca)₂Si₅N₈:Eu²⁺; (Sr,Ca)AlSiN₃:Eu²⁺; Y₂O₃:Eu³⁺,Bi³⁺;(Ca,Sr)S:Eu²⁺; CaLa₂S₄:Ce³⁺; (Sr,Ca,Ba)₂P₂O₇:Eu²⁺,Mn²⁺;(Ca,Sr)₁₀(PO₄)₆(F,Cl):E²⁺,Mn²⁺; (Y,Lu)₂WO₆:Eu³⁺,Mo⁶⁺;(Gd,Y,Lu,La)₂O₃:Eu³⁺,Bi³⁺; (Gd,Y,Lu,La)₂O₂O₂S:Eu³⁺,Bi³⁺;(Gd,Y,Lu,La)BO₃:Eu³⁺,Bi³⁺; (Gd,Y,Lu,La)(P,V)O₄:Eu³⁺,Bi³⁺ and(Ba,Sr,Ca)MgP₂O₇:Eu²⁺,Mn²⁺.

In one exemplary embodiment the halosilicate phosphor may have a peakwavelength of about 520 nm to about 670 nm in emission spectra.

In exemplary embodiments the white light emitting device may be used ina traffic light, a light source of communication devices, a backlight ofa display device, or illumination applications.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects, advantages, and features of this disclosurewill become apparent and more readily appreciated from the followingdescription of the embodiments, taken in conjunction with theaccompanying drawings of which:

FIG. 1 is a schematic view illustrating an exemplary embodiment of thestructure of a white light emitting device;

FIG. 2 is a graph showing intensity (arbitrary units, a.u.) versuswavelength (nanometers, nm) for an emission spectra of a halosilicatephosphor prepared according to Example 1 and resulting from exciting thehalosilicate phosphor with a light having a wavelength of 400 nm;

FIG. 3 is a graph showing intensity (a.u.) versus wavelength (nm) for anemission spectra of a halosilicate phosphor prepared according toExample 2 and resulting from exciting the halosilicate phosphor with alight having a wavelength of 400 nm;

FIG. 4 is a graph showing intensity (a.u.) versus wavelength (nm) for anemission spectra of a halosilicate phosphor prepared according toExample 3 and resulting from exciting the halosilicate phosphor with alight having a wavelength of 400 nm;

FIG. 5 is a graph showing the normalized intensity (a.u.) versuswavelength (nm) for an emission spectra of the halosilicate phosphorsprepared according to Example 1, Comparative Example 1 and ComparativeExample 3;

FIG. 6 is a graph showing the chromaticity coordinates (x, y) of thehalosilicate phosphors prepared according to Example 1, ComparativeExample 1, Comparative Example 3, and a blue light emitting diode(“LED”); and

FIG. 7 is a graph showing intensity (a.u.) versus scattering angle 2θ(degree) for the X-ray diffraction (“XRD”) of the halosilicate phosphorsprepared according to Example 1, Example 2, Example 3 and ComparativeExample 1.

DETAILED DESCRIPTION

This disclosure will now be described more fully hereinafter withreference to the accompanying drawings, in which embodiments of thedisclosure are shown. The exemplary embodiments may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein. Rather these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the concepts described herein to those skilled in the art.Like reference numerals refer to like elements throughout.

It will be understood that when an element is referred to as being “on”another element, it can be directly on the other element or interveningelements may be present therebetween. In contrast, when an element isreferred to as being “directly on” another element, there are nointervening elements present. As used herein, the term “and/or” includesany and all combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, third etc.may be used herein to describe various elements, components, regions,layers and/or sections, these elements, components, regions, layersand/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer orsection from another element, component, region, layer or section. Thus,a first element, component, region, layer or section discussed belowcould be termed a second element, component, region, layer or sectionwithout departing from the teachings herein.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” or “includes” and/or “including” when used in thisspecification, specify the presence of stated features, regions,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,regions, integers, steps, operations, elements, components, and/orgroups thereof.

Furthermore, relative terms, such as “lower” or “bottom” and “upper” or“top,” may be used herein to describe one element's relationship toanother elements as illustrated in the Figures. It will be understoodthat relative terms are intended to encompass different orientations ofthe device in addition to the orientation depicted in the Figures. Forexample, if the device in one of the figures is turned over, elementsdescribed as being on the “lower” side of other elements would then beoriented on “upper” sides of the other elements. The exemplary term“lower”, can therefore, encompasses both an orientation of “lower” and“upper,” depending on the particular orientation of the figure.Similarly, if the device in one of the figures is turned over, elementsdescribed as “below” or “beneath” other elements would then be oriented“above” the other elements. The exemplary terms “below” or “beneath”can, therefore, encompass both an orientation of above and below.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the relevant art. It will be further understoodthat terms, such as those defined in commonly used dictionaries, shouldbe interpreted as having a meaning that is consistent with their meaningin the context of the relevant art and the present disclosure, and willnot be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Exemplary embodiments are described herein with reference to crosssection illustrations that are schematic illustrations of idealizedembodiments of the present disclosure. As such, variations from theshapes of the illustrations as a result, for example, of manufacturingtechniques and/or tolerances, are to be expected. Thus, embodiments ofthe present disclosure should not be construed as limited to theparticular shapes of regions illustrated herein but are to includedeviations in shapes that result, for example, from manufacturing. Forexample, a region illustrated or described as flat may, typically, haverough and/or nonlinear features. Moreover, sharp angles that areillustrated may be rounded. Thus, the regions illustrated in the figuresare schematic in nature and their shapes are not intended to illustratethe precise shape of a region and are not intended to limit the scope ofthis disclosure.

Hereinafter, the exemplary embodiments will be described in detail withreference to the accompanying drawings.

All methods described herein can be performed in a suitable order unlessotherwise indicated herein or otherwise clearly contradicted by context.The use of any and all examples, or exemplary language (e.g., “suchas”), is intended merely for illustration and does not pose a limitationon the scope of the disclosure unless otherwise claimed. No language inthe specification should be construed as indicating that any non-claimedelement is essential.

One or more exemplary embodiments include a halosilicate phosphorrepresented by Formula 1.

p(Ca_(1-x)M¹ _(x))O.qM²O₂.rM³A₂:sM⁴   Formula 1

-   -   wherein M¹ comprises at least one selected from a group        consisting of Sr²⁺ and Ba²⁺;    -   M² comprises at least one selected from a group consisting of        Si⁴⁺ and Ge⁴⁺;    -   M³ comprises at least one selected from a group consisting of        Ca²⁺, Sr²⁺ and Ba²⁺;    -   M⁴ comprises at least one selected from a group consisting of        Eu²⁺, Mn²⁺, Sb²⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Tb³⁺, Dy³⁺, Ho³⁺,        Er³⁺, Yb³⁺ an Bi³⁺;    -   A comprises at least one selected from a group consisting of F⁻,        Cl⁻, Br⁻ and I⁻; and    -   wherein 0≦x<1, 1.8≦p≦2.2, 0.8≦q≦1.2, 1<r/q<3 and 0<s<0.5.

In Formula 1, “.” indicates the combination of a metal oxide and a metalhalide reacting in order to prepare a phosphor according to an exemplaryembodiment.

In exemplary embodiments the halosilicate phosphor may absorb light inthe wavelength range of about 360 nanometers (nm) to about 470 nm. Inother exemplary embodiments the halosilicate phosphor may emit visiblelight having a peak wavelength of from about 520 nm to about 670 nmaccording to the compositions of the metal ions. Thus, the halosilicatephosphor is a material having excellent emission properties over a widerange of wavelengths from green to orange. In one exemplary embodiment,the halosilicate phosphor has a far wider full width at half maximum(“FWHM”) in a wavelength range of about 125 to about 220 nm as comparedto a conventional Y₃Al₅O₁₂:Ce³⁺ phosphor or Sr₂SiO₄:Eu²⁺ phosphor. Inone exemplary embodiment the halosilicate phosphor may be applied to ablue light emitting diode (“LED”) either alone or with a small amount ofan additional phosphor. The halosilicate phosphor may be applied to anultraviolet light emitting diode (“UV LED”) with the addition of blue,green and/or red phosphors in order to fabricate a white light emittingdevice having excellent color rendering properties and excellent colorreproduction properties. The wide band emission may occur since at leasttwo phases of the halosilicate are mixed. That is, a relative intensityof light emitted from each of the phases of the halosilicate phosphormay vary according to the r/q ratio, which is defined as the mixingratio where r is a halide and q is an oxide.

In exemplary embodiments r is selected from at least one of a groupconsisting of Ca, Sr and Ba halides and q is selected from at least oneof a group consisting of Si and Ge oxides. The halide and oxide areselected in order to change the overall tones of the emission. In theyellow light emission, the contribution of the green light emissionincreases as the r/q ratio increases, and the contribution of the orangelight emission increases as the r/q ratio decreases. Thus, if theluminosity factor of the light and the color rendering properties aretaken into consideration, a high quality yellow phosphor may be combinedwith a blue LED to generate a white light in a range of from about1<r/q<about 3 may be prepared.

In exemplary embodiments the halosilicate phosphor may be prepared froma) a Ca oxide alone or from a mixture of a Ca oxide mixed with at leastone of a Sr oxide and a Ba oxide; b) a Si oxide alone or from a mixtureof a Si oxide and a Ge oxide; c) from an Eu oxide alone or from amixture of an Eu oxide and an oxide of at least one metal selected froma group consisting of Mn, Sb, Ce, Pr, Nd, Sm, Tb, Dy, Ho, Er, Yb and Biand d) from a halide of Ca, Sr, Ba or any mixture thereof.

In exemplary embodiments the amount of the a), b), c) and d) componentsmay be selected such that p, q, r and s are within the ranges describedin Formula 1.

In one exemplary embodiment, if a Ca oxide is mixed with at least one ofthe group consisting of a Sr oxide and a Ba oxide, then the molar ratioof (Sr+Ba):Ca may be in a range of about 0.0001:1 to about 2:3.

In addition, in one exemplary embodiment, if a Si oxide is mixed with aGe oxide, the molar ratio of Ge:Si may be in a range of about 0.0001:1to about 1:3.

In addition, in one exemplary embodiment, if an Eu oxide is mixed withan oxide of at least one metal selected from a group consisting of Mn,Sb, Ce, Pr, Nd, Sm, Tb, Dy, Ho, Er, Yb and Bi, then the molar ratio ofA:Eu may be in a range of about 0.0001:1 to about 9:1, wherein Aincludes at least one metal selected from the group consisting of Mn,Sb, Ce, Pr, Nd, Sm, Tb, Dy, Ho, Er, Yb and Bi.

Herein, the reactant is shown as an oxide since the reactant turns tothe oxide form at a high temperature synthesis even if the reactant is aprecursor of any other form such as a carbonate, a nitrate, a hydroxide,or an acetate. Therefore, if a molar ratio of an oxide of the startingmaterial is within the above-described range, the reaction precursor maybe present in various other forms such as a carbonate, a nitrate, ahydroxide, an acetate, etc. in addition to the metal oxide. Among thereaction precursors of the above-described halosilicate phosphor, ahalide of Ca, Sr, Ba or mixtures thereof may function as a constituentelement of a phosphor having at least two phases. Since the meltingpoint of the Ca, Sr or Ba halide is equal to or less than a temperatureof about 800 degrees Celsius (° C.), the Ca, Sr or Ba halide functionsas a flux to increase the crystallinity of the halosilicate at atemperature close to about 1000° C. Thus, there is no need to add amaterial used as a flux in order to produce high-quality crystals.

In exemplary embodiments, the white light emitting device may produce awhite light having a high color rendering index, and thus may be appliedas a high-quality illuminating application which is required in, forexample, medical applications, food exhibitions, museums, and artgalleries.

In exemplary embodiments the halosilicate phosphor may be prepared usingany various known methods, such as a solid phase method, a liquid phasemethod, or a vaporous phase method, without limitation.

In one exemplary embodiment if the halosilicate phosphor is preparedusing the solid phase method, a mixture of powder of a Ca oxide (aloneor in a mixture of a Ca oxide with at least one of a Sr oxide or a Baoxide); a Si oxide (alone or in a mixture of a Si oxide with a Geoxide); an Eu oxide (alone or in a mixture of an Eu oxide with an oxideof at least one metal selected from a group consisting of Mn, Sb, Ce,Pr, Nd, Sm, Tb, Dy, Ho, Er, Yb and Bi); and a halide of Ca, Sr, Ba ormixtures thereof may be prepared. Then, the obtained powder mixture issintered at a temperature of about 700° C. to about 1200° C. in areducing atmosphere of a gaseous mixture of hydrogen and nitrogen.Herein, the amount of hydrogen in the gaseous mixture is controlled tobe at least 5 volume percent (vol. %).

If the Eu oxide is used either alone or in a mixture of an Eu oxide withan oxide of at least one metal selected from a group consisting of Mn,Sb, Ce, Pr, Nd, Sm, Tb, Dy, Ho, Er, Yb and Bi. The Eu oxide or Eu oxidemixture is then doped into the inner surface of the phosphor crystalswhere it functions as an activator when the halosilicate phosphor emitslight.

If the synthetic temperature is lower than 700° C., the synthesisreaction may not be thoroughly performed and the intensity of emissionis lower than at a desired level. On the other hand, if the synthetictemperature is higher than 1200° C., the target product is melted and aglass phase is formed. Thus, the intensity of emission is reduced anddesired physical properties may not be obtained.

In one exemplary embodiment the obtained sintered product may bepulverized into a powder and washed with distilled water to obtain thedesired phosphor.

One or more exemplary embodiments include a white light emitting deviceincluding the halosilicate phosphor described above.

In exemplary embodiments of the white light emitting device, a LED maybe either a blue LED or an UV LED. An excitation light source of the LEDmay have a peak wavelength of about 360 to about 470 nm.

In exemplary embodiments of the white light emitting device, thehalosilicate phosphor may have a peak wavelength of about 520 to about670 nm in the emission spectra.

Exemplary embodiments of the white light emitting device may furtherinclude at least one selected from a group consisting of a bluephosphor, a green phosphor and a red phosphor.

The blue phosphor may include at least one selected from a groupconsisting of (Sr,Ba,Ca)₅(PO₄)₃Cl:Eu²⁺; BaMg₂Al₁₆O₂₇:Eu²⁺;Sr₄Al₁₄O₂₅:Eu²⁺; BaAl₈O₁₃:Eu²⁺; BaMgAl₁₀O₁₇:Eu²⁺, Sr₂Si₃O₈.2SrCl₂:Eu²⁺;Ba₃MgSi₂O₈:Eu²⁺; and (Sr,Ca)₁₀(PO₄)₆.nB₂O₃:Eu²⁺.

The green phosphor may include at least one selected from a groupconsisting of (Ba,Sr,Ca)₂SiO₄:Eu²⁺; Ba₂MgSi₂O₇:Eu²⁺; Ba₂ZnSi₂O₇:Eu²⁺;BaAl₂O₄:Eu²⁺; SrAl₂O₄:Eu²⁺; BaMgAl₁₀O₁₇:Eu²⁺, Mn²⁺ andBaMg₂Al₁₆O₂₇:Eu²⁺,Mn²⁺.

In exemplary embodiments the red phosphor may include at least oneselected from a group consisting of (Ba,Sr,Ca)₂Si₅N₈:Eu²⁺;(Sr,Ca)AlSiN₃:Eu²⁺; Y₂O₃:Eu³⁺,Bi³⁺; (Ca,Sr)S:Eu²⁺; CaLa₂S₄:Ce³⁺;(Sr,Ca,Ba)₂P₂O₇:Eu²⁺,Mn²⁺; (Ca,Sr)₁₀(PO₄)₆(F,Cl) :Eu²⁺, Mn²⁺;(Y,Lu)₂WO₆:Eu³⁺,Mo⁶⁺; (Gd,Y,Lu,La)₂O₃:Eu³⁺,Bi³⁺;(Gd,Y,Lu,La)₂O₂S:Eu³⁺,Bi³⁺; (Gd,Y,Lu,La)BO₃:Eu³⁺,Bi³⁺;(Gd,Y,Lu,La)(P,V)O₄:Eu³⁺,Bi³⁺ and (Ba,Sr,Ca)MgP₂O₇:Eu²⁺,Mn²⁺.

FIG. 1 is a schematic view illustrating an exemplary embodiment of thestructure of a white light emitting device. The white light emittingdevice illustrated in FIG. 1 is a polymer lens type surface-mountedwhite light emitting device. In an exemplary embodiment an epoxy lens isused as the polymer lens.

Referring to FIG. 1, the UV LED chips 10 are die-bonded to the electriclead wires 30 through the gold wires 20. The epoxy mold layers 50 areformed so as to include the phosphor compositions containing ahalosilicate phosphor 40 according to an exemplary embodiment. Areflective film coated with aluminum or silver is formed on an innersurface of the mold 60 to reflect light upward from the UV LED chips 10and to limit the epoxy of the epoxy mold layers 50 to an appropriateamount.

An epoxy dome lens 70 is disposed above the epoxy mold layer 50. Theshape of the epoxy dome lens 70 may be varied according to a desiredorientation angle.

The white light emitting device according to one or more exemplaryembodiments is not limited to the structure illustrated in FIG. 1. Forexample, the white light emitting device may be a phosphor-mounted lightemitting device, a lamp-type light emitting device, a PCB-typesurface-mounted light emitting device or the like.

Meanwhile, the halosilicate phosphor according to an exemplaryembodiment may be applied to a lamp such as a mercury lamp or a xenonlamp, or to a photoluminescent liquid crystal display (“PLLCD”), inaddition to a white light emitting device as described above.

Hereinafter, one or more exemplary embodiments will be described infurther detail with reference to the following examples. The followingexamples are for illustrative purposes only and are not intended tolimit the scope of the one or more exemplary embodiments.

Example 1 Synthesis of 2CaO.SiO₂.1.2CaCl₂:0.025Eu²⁺

A phosphor was prepared using a solid phase reaction method. A sourcepowder including 6.66 grams (g) of CaCO₃, 2 g of SiO₂, 0.30 g of Eu₂O₃and 5.87 g of CaCl₂.2H₂O was mixed using a mortar for 30 minutes. Themixed source powder was then sintered in an atmosphere of H₂/N₂=5/95 at1000° C. for 8 hours. The resultant sintered sample was then pulverizedusing the mortar and washed with distilled water at room temperature toobtain a phosphor in powder form.

The resultant phosphor has a FWHM of 200 nm in an emission spectrum.

Example 2 Synthesis of 2CaO.SiO₂.1.7CaCl₂:0.025Eu²⁺

A phosphor in powder form was manufactured in the same manner as inExample 1, except that 8.7 g of CaCl₂.2H₂O was used instead of 5.87 g ofCaCl₂.2H₂O.

The resultant phosphor has a FWHM of 165 nm in an emission spectrum.

Example 3 Synthesis of 2CaO.SiO₂.2.1CaCl₂:0.025Eu²⁺

A phosphor in powder form was manufactured in the same manner as inExample 1, except that 10.7 g of CaCl₂.2H₂O was used instead of 5.87 gof CaCl₂.2H₂O.

The resultant phosphor has a FWHM of 130 nm in an emission spectrum.

Comparative Example 1 Synthesis of Ca₃SiO₄Cl₂:Eu²⁺

A phosphor was prepared using a solid phase reaction method. A sourcepowder including 6.66 g of CaCO₃, 2 g of SiO₂, 5.00 g of CaCl₂.2H₂O and0.30 g of Eu₂O₃ was mixed using a mortar for 30 minutes. The mixedpowder was then placed in an alumina reaction vessel and sintered in anatmosphere of H₂/N₂=5/95 at 1000° C. for 8 hours. The resultant sinteredsample was then pulverized using the mortar and washed with distilledwater at room temperature to obtain a phosphor in powder form.

The resultant phosphor has a FWHM of 100 nm in an emission spectrum.

Comparative Example 2 Synthesis of Y₃Al₅O₁₂:Ce³⁺

A phosphor was prepared using a solid phase reaction method. A sourcepowder including 4.00 g of Y₂O₃, 3.20 g of Al₂O₃ and 0.34 g of CeO₂ wasmixed using a mortar for 30 minutes. The mixed powder was then placed inan alumina reaction vessel and sintered in an atmosphere of H₂/N₂=5/95at 1400° C. for 6 hours. The resultant sintered sample was thenpulverized using the mortar and washed with distilled water at roomtemperature to obtain a phosphor in powder form.

The resultant phosphor has a FWHM of 120 nm in an emission spectrum.

Comparative Example 3 Synthesis of Sr₂SiO₄:Eu²⁺

A phosphor was prepared using a solid phase reaction method. A sourcepowder including 8.00 g of SrCO₃, 1.65 g of SiO₂ and 0.12 g of Eu₂O₃ wasmixed using a mortar for 30 minutes. The mixed powder was then placed inan alumina reaction vessel and sintered in an atmosphere of H₂/N₂=5/95at 1300° C. for 6 hours. The resultant sintered sample was thenpulverized using the mortar and washed with distilled water at roomtemperature to obtain a phosphor in powder form.

The resultant phosphor has a FWHM of 100 nm in an emission spectrum.

FIGS. 2 through 4 are graphs of intensity (a.u.) versus wavelength (nm)for the emission spectra of the phosphors prepared in Examples 1 through3, and resulting from the phosphors being excited with a light having awavelength of 400 nm. FIG. 5 is a graph showing the normalized intensity(a.u.) versus wavelength (nm) for the emission spectra of the phosphorsprepared in Example 1 and Comparative Examples 2 and 3. Referring toFIG. 5, it can be seen that the FWHM of a phosphor according to anexemplary embodiment is relatively wide.

FIG. 6 is a graph showing the chromaticity coordinates (x, y) of thephosphors prepared in Example 1 and Comparative Examples 2 and 3.Referring to FIG. 6, it can be seen that white light may be emitted byapplying the phosphor to a blue LED in combination with Y₃Al₅O₁₂:Ce³⁺ orSr₂SiO₄:Eu²⁺.

FIG. 7 is a graph showing intensity (a.u.) versus scattering angle 2θ(degree) for the X-ray diffraction (“XRD”) of the phosphors prepared inExamples 1 through 3 according to exemplary embodiments and ComparativeExample 1. Referring to FIG. 7, as the amount of CaCl₂ in the reactionprecursor increases within a constant range, the relative intensity ofthe new peak, which does not appear in Comparative Example 1, alsoincreases. Therefore, a halosilicate phosphor according to an exemplaryembodiment is not a single phase material but is instead a mixture of atleast two phases. In addition, as the r/q ratio increases to 1.7 and 2.1from 1.2, a relative amount of the new phase increases compared to theknown Ca₃SiO₄Cl₂ phase. In addition, it can be seen that the change inthe emission peak of FIGS. 2 to 4 originates from the increase of thenew phase.

As described above, according to one or more of the above exemplaryembodiments, the halosilicate phosphor has a large FWHM, and the whitelight emitting device including the halosilicate phosphor has excellentcolor rendering properties.

It should be understood that the exemplary embodiments described hereinshould be considered in a descriptive sense only and not for thepurposes of limitation. Descriptions of features or aspects within eachembodiment should typically be considered as available for other similarfeatures or aspects in other embodiments.

1. A halosilicate phosphor represented by Formula 1:p(Ca_(1-x)M¹ _(x))O.qM²O₂.rM³A₂:sM⁴   Formula 1 wherein M¹ comprises atleast one selected from a group consisting of Sr²⁺ and Ba²⁺; M²comprises at least one selected from a group consisting of Si⁴⁺ andGe⁴⁺; M³ comprises at least one selected from a group consisting ofCa²⁺, Sr²⁺ and Ba²⁺; M⁴ comprises at least one selected from a groupconsisting of Eu²⁺, Mn²⁺, Sb²⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Tb³⁺, Dy³⁺,Ho³⁺, Er³⁺, Yb³⁺ and Bi³⁺; A comprises at least one selected from agroup consisting of F⁻, Cl⁻, Br⁻ and I⁻; and wherein 0≦x<1, 1.8≦p≦2.2,0.8≦q≦1.2, 1<r/q<3 and 0<s<0.5.
 2. The halosilicate phosphor of claim 1,wherein the halosilicate phosphor has a full width at half maximum ofabout 125 nm to about 220 nm in an emission spectra.
 3. A white lightemitting device comprising a light emitting diode and a halosilicatephosphor represented by Formula 1:p(Ca_(1-x)M¹ _(x))O.qM²O₂.rM³A₂:sM⁴   Formula 1 wherein M¹ comprises atleast one selected from a group consisting of Sr²⁺ and Ba²⁺; M²comprises at least one selected from a group consisting of Si⁴⁺ andGe⁴⁺; M³ comprises at least one selected from a group consisting ofCa²⁺, Sr²⁺ and Ba²⁺; M⁴ comprises at least one selected from a groupconsisting of Eu²⁺, Mn²⁺, Sb²⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Tb³⁺, Dy³⁺,Ho³⁺, Er³⁺; Yb³⁺ and Bi³⁺; A comprises at least one selected from agroup consisting of F⁻, Cl⁻, Br⁻ and I⁻; 0≦x<1, 1.8≦p≦2.2, 0.8≦q≦1.2,1<r/q<3 and 0<s<0.5.
 4. The white light emitting device of claim 3,wherein the light emitting diode is at least one selected from a groupconsisting of a blue light emitting diode and an ultraviolet lightemitting diode.
 5. The white light emitting device of claim 3, furthercomprising at least one selected from a group consisting of a bluephosphor, a green phosphor and a red phosphor.
 6. The white lightemitting device of claim 5, wherein the blue phosphor comprises at leastone selected from a group consisting of (Sr,Ba,Ca)₅(PO₄)₃Cl:Eu²⁺;BaMg₂Al₁₆O₂₇:Eu²⁺; Sr₄Al₁₄O₂₅:Eu²⁺; BaAl₈O₁₃:Eu²⁺; BaMgAl₁₀O₁₇:Eu²⁺;Sr₂Si₃O₈.2SrCl₂:Eu²⁺; Ba₃MgSi₂O₈:Eu²⁺ and (Sr,Ca)₁₀(PO₄)₆.nB₂O₃:Eu²⁺. 7.The white light emitting device of claim 5, wherein the green phosphorcomprises at least one selected from a group consisting of(Ba,Sr,Ca)₂SiO₄:Eu²⁺; Ba₂MgSi₂O₇:Eu²⁺; Ba₂ZnSi₂O₇:Eu²⁺; BaAl₂O₄:Eu²⁺;SrAl₂O₄:Eu²⁺; BaMgAl₁₀O₁₇:Eu²⁺, Mn²⁺ and BaMg₂Al₁₆O₂₇:Eu²⁺, Mn²⁺.
 8. Thewhite light emitting device of claim 5, wherein the red phosphorcomprises at least one selected from a group consisting of(Ba,Sr,Ca)₂Si₅N₈:Eu²⁺; (Sr,Ca)AlSiN₃:Eu²⁺; Y₂O₃:Eu³⁺,Bi³⁺;(Ca,Sr)S:Eu²⁺; CaLa₂S₄:Ce³⁺; (Sr,Ca,Ba)₂P₂O₇:Eu²⁺,Mn²⁺;(Ca,Sr)₁₀(PO₄)₆(F,Cl):Eu²⁺,Mn²⁺; (Y,Lu)₂WO₆:Eu³⁺,Mo⁶⁺;(Gd,Y,Lu,La)₂O₃:Eu³⁺,Bi³⁺; (Gd,Y,Lu,La)₂O₂S:Eu³⁺,Bi³⁺;(Gd,Y,Lu,La)BO₃:Eu³⁺,Bi³⁺; (Gd,Y,Lu,La)(P,V)O₄:Eu³⁺, Bi³⁺ and(Ba,Sr,Ca)MgP₂O₇:Eu²⁺,Mn²⁺.
 9. The white light emitting device of claim3, wherein the halosilicate phosphor has a peak wavelength of about 520nm to about 670 nm in an emission spectra.
 10. The white light emittingdevice of claim 3, wherein the white light emitting device is used in atraffic light, as a light source for communication devices, as abacklight for a display device, or as an illumination application.